I've been testing around 163 the last couple weeks, but unlike when I first got into the low 160's with a solid score for each section ( at least for the time), now I'm having a hard time stringing together really good sections. If I could consistently put them together for the same test I would probably be in the upper 160's. How long did it take to get this consistency?

if you look very closely at the questions you get wrong - it may be that there are particular types you excel at and some that you struggle with. in turn, if practice tests have greater or fewer questions of certain types your score may fluctuate accordingly. just focus on being consistent on different question types and drill the ones you have the hardest time with. g'luck!

The variation will happen each time...it can often be just variances in difficulty compounded by variances in concentration.

Don't worry too much about this in the short term - you will primarily want to drill the question types that you have issues with but those issues with consistency can diminish in time with increased focus over the length of the entire test.